Due to some drawbacks of well logging instruments for hydrocarbon resource exploration utilizing gamma ray sources and gamma ray detectors, some well logging instruments instead utilize x-ray generators and x-ray detectors. As explained in U.S. Pat. No. 7,668,293 to Wraight et al., which is assigned to the same assignee as the present disclosure and is hereby incorporated herein in its entirety by reference, an x-ray generator may include an electron accelerator and a target. The electron accelerator accelerates electrons toward the target at a sufficient speed so that when the electrons are stopped by the target (which is sufficiently thick to stop electrons striking it), x-ray photons are produced, e.g., by Bremsstrahlung radiation.
Various advances in x-ray sources, x-ray detectors, and methods of analyzing the data generated thereby have been made, examples of which are set forth in U.S. Pat. No. 7,960,687 to Simon et al., U.S. Pat. No. 7,817,781 to Wraight et al., and U.S. Pat. No. 7,564,948 to Wraight et al., all of which are assigned to the same assignee as the present disclosure and are hereby incorporate herein in their entireties by reference. However, some particle accelerator configurations may have drawbacks associated therewith. For example, commonly used cathodes in electron accelerators emit not only electrons, but also conductive particles. These conductive particles may build up on insulating surfaces inside the electron accelerator, thereby changing the characteristics of those insulating surfaces. This in turn may undesirably affect the electric field inside the electron accelerator, and therefore alter the focus point of the electron beam. As a result, the electron beam may not strike the intended portion of the target. This may degrade the performance of the x-ray generator, and thus in the context of a well logging application, the performance of the well logging instrument utilizing the x-ray generator.